Automatic switching system



p 9 1930- A. E. ANDERSON 1,756,344

AUTOMATIC SWITCHING SYSTEM Original Filed July 18, 1928 Inventor. Ava/LE. Anders on b9 00% H I s Attorney.

Patented Apr. 29, 1930 UNITED STATES PATENT FFicE ARVID E. ANDERSON, F LANSDOWNE, PENNSYLVANIA, ASSIGNOR T0 GENERAL ELEG- TRIC COMPANY, A CORPORATION OF NEW YORK AUTOMATIC SWITCHING SYSTEM Application filed. July 18, 1928, Serial No. 293,629.

My invention relates to automatic switching systems and particularly to systems for controlling the connections between a plurality of sources of current and a load circuit so that when a source which is supplying current to the load circuit fails or is disconnected from the load circuit by an overload thereon another source is automatically connected to the load circuit to restore the supply oi' current thereto. One object of my invention is to provide an improved arrange ment of apparatus for accomplishing this result.

In certain systems of distribution, such for example as a railway signaling system, it is essential that any interruption in the supply of current to the load circuit be as short as possible. Therefore, it is customary to have at least two sources of current available, one of which is normally connected to the load circuit and the other of which is normally disconnected from the load circuit and is arranged to be connected thereto whenever the load circut is'deenergized due either to the failure of the first source or a disconnection hereof from the load circuit. It is also customary to provide each source with a timing device which, when operated, is arranged to connect the associated source to the load circuit a plurality of times with predetermined time intervals between successive connections. One way in which operation of such timing devices has been effected is when the associated source is energized and disconnected from the load circuit, and the load circuit voltage decreases below a predetermined value. In accordance with my invention I provide an arrangement whereby the operation of a timing device associated with a source it effected only when the associated source is disconnected from the load circuit by an overload thereon and whereby each source is immediately connected to the load circuit independently of the associated timing device and without effecting the operation thereof whenever the voltage of the other source fails while supplying current to the load circuit.

My invention will be better understood from the following description taken in con- Renewed February 27, 1930.

nection with the accompanying drawing and its scope will be pointed out in the appended claims.

Referring to the accompanying drawing which is a diagram of a system of distribution embodying my invention, 1 represents a load circuit, such as a section of a railway signaling system, which is arranged to be supplied with current at different points by two suitable sources of current 2 and 3. The sources 2 and 3 are arranged to be connected to the load circuit 1 by switches 4t and 5 respectively which may be of any suitable type examples of which are well known in the art.

For controlling the opening and closing of each switch, I provide a control arrangement for effecting the opening of the switch when the associated source fails or is overloaded and for effecting the automatic closing 01 the switch when it is open, the associated source is energized and the load circuit is deenergized.

In order to simplify the disclosure, however, I have shown in detail only the control arrangement for the switch 1- but it is to be understood that the switch 5 may be provided with a similar control arrangement.

As shown in the drawing, the switch 4; is of the well known latched-in type and is provided with a closing coil 6 which when energized closes the switch, a latch 7 for holding the switch in its closed position after the closing coil 6 is deenergized, an overload trip coil 8 which when energized releases the latch to permit the switch to open and a low voltage release magnet 9 which is connected so as to be energized in response to the voltage of the associated source 2 and which is arranged to release the latch 7 when the voltage of the source 2 is below a predetermined value. The overload trip coil 8 and a lockout relay 10 associated therewith are arranged in any suitable manner so as to be responsive to the current output of the source 2. As shown in the drawing the coil 8 and relay 10 are arranged to be connected in series across a suitable source of control current whenever the current output of the source 2 is sufi icient to cause the overload relay 11, which is connected in any suitable manner so as to be responsive to the current output of the source 2, to close its contacts 12. Preferably the under-voltage trip 9 is provided with a slight time delay in order to insure that when an overload occurs, which might reduce the load circuit voltage sufficiently to operate the undervoltage trip, the overload relay 11 is operated to effect the energization of the lockout relay 10.

As shown, the lockout relay 10 is of the well known type which is held in its energized position by a latch 13 until a release coil 14 associated therewith is energized.

For effecting the immediate closing of the switch 4 when the voltage across the load circuit decreases below a predetermined value due to the failure of the other source 3 while it is supplying current to the load, I provide a voltage responsive relay 16 which is connected across the load circuit 1. This relay 16 when deenergized is arranged, when the lookout relay 10 is also in its deenergized position and the source 2 is energized, to complete a circuit for the control relay 17 which when energized effects the energization of the closing coil 6 to close the switch 4 and connect the source 2 to the load circuit.

In order to effect a predetermined number of reclosures of the switch 4 when it is opened due to an overload on the load circuit, I provide a timing device 20 which is arranged to be set into operation when the source 2 is energized, as indicated by the energization of a voltage relay 21 connected across the source 2, the switch 4 is open, and the lookout relay 10 is in its energized position. The timing device 20 when operated is arranged to effect the closing of the switch 4 a predetermined number of times with predetermined time intervals between successive closures of the switch. If at the end of a predetermined time interval after the operation of the timing device 20 has been effected, the switch 4 is closed, or the switch 4 is open and the voltage relay 16 is energized, the timing deice 20 is arranged to effect the energization of the release coil 14 of the lockout relay 10 so that it is restored to its normal position. If, however, the switch 4 is open and the load circuit voltage is not restored to normal at the end of said predetermined time interval the timing device 20 is arranged to effect the operation of a lockout relay 22 which is so connected and arranged that when it is energized further operation of the timing device 20, to effect a reclosure of the switch, is prevented until the lockout relay 22 has been reset manually.

As shown in the drawing, the timing device 20 comprises a timer 23 which is driven by a motor 24 permanently connected to a suitable source of current such as the source 2. The timer 23 is normally prevented from rotating by a movable stop 25 which engages a projection 26 on the timer 23. The opera tion of the timer is effected by the energization of a release magnet 27 which when energized moves the stop 25 out of engagement with the projection 26. As the timer rotates it is arranged to close the contacts 28 and 29 successively a predetermined number of times with predetermined time intervals between successive closings of the same contacts. The contacts 28 control the circuit of a control relay 30 so that it the other conditions which control the circuit of the relay 30 are such that the switch 4 should be closed at the time the contacts 28 are closed, the relay 30 is energized and completes a locking. circuit for itself which is independent of the contacts 28. hen the timer 23 subsequently closes its contacts 29 a circuit for the control relay 17 is completed to effect the closing of the switch 4 if the relay 30 is energized at the same time. After the timer has been in operation a predetermined time and has effected a predetermined number of closures of the contacts 28 and 29, it is arranged to close its lockout contacts 31. The closing of these contacts 31 controls the energization of the release coil 14 of the lockout relay 10 and the operating coil of the lockout relay 22 and thereby determines whether the lockout relay 10 is restored to its normal position so that the timing device may operate to effect further reclosures of the switch 4 or whether the controlling devices for the switch. 4 are rendered inoperative to effect farther reclosures of the switch 4.

The operation of the arrangement shown in the drawing is as follows:

When the switch 5 is closed so that the source 3 is supplying current to the load circuit 1, the automatic control equipment associated with the source 4 is in the position shown. It will be assumed first that the voltage across the load circuit 1 decreases below a predetermined value due to a voltage failure of the source 3. Therefore the voltage relay 16 associated with switch 4 opens its contacts 32 and closes its contacts 33, 34 and 42. The voltage failure of the source 3 effects the deenergization of the undervoltage release magnet 9 associated with the switch 5 so that this switch is opened and the source 3 is disconnected from the load circuit.

The closing of the contacts 33 of the relay 16 associated with switch 4 completes a circuit for the control relay 17 associated therewith. This circuit is from one side of a suitable source of control current through auxiliary contacts 35 on the switch 4, coil of relay 17, contacts 36 of the undervoltage release magnet 9, contacts 33 of the voltage relay 16, contacts 37 of the lockout relay 10 to the other side of the control circuit. The closing of the contacts 33 of the relay 16 associated with switch 5 does not complete a similar circuit for its respective control relay 17 as its circuit is open at the contacts 36 of the associated low voltage release magnet 9.

The energization of the control relay 17 associated with switch 4 completes a circuit for the closing coil 6 to close the switch 4 and connect the source 2 to the load circuit 1. The circuit of the closing coil 6 includes the auxiliary contacts 35 on the switch 4 and the contacts 38 of the control relay 17. As soon as the switch 4 closes the voltage relay 16 associated with the switches 4 and 5 are restored to their normal positions. Therefore, the circuit of the closing coil 6 for the switch 5 is not completed to close the switch 5 and reconnect the source 3 to the load circuit 1 when the voltage of the source 3 is subsequently restored to normal and the under-voltage release magnet 9 associated therewith closes its contacts 36. It will be observed that when the closing of the switch 4 is effected in response to a voltage failure of the other source the operation of the timing device 20 associated with the source 4 is not efiected.

It will be assumed now that while the switch 4 is closed and the source 2 is supplying current to the load circuit 1, an overload occurs on the load circuit so that the overload relay 11 associated with the source 2 closes its contacts 12 and completes a circuit for the overload trip coil 8 and the operating coil of the lockout relay 10. The energization of the overload trip coil 8 releases the latch 7 so that the switch 4 is opened and the load circuit 1 is deenergized. he voltage relay 16 associated with the switch 5 closes its contacts 33 and, assuming source 3 to be energized, effects in a manner similar to that above described in connection with switch 4, the immediate closing of the switch 5. If the overload is still connected to the load circuit when the switch 5 closes, the overload relay 11 associated therewith will effect the opening of the switch 5 in the same manner that the overload relay 11 effected the opening of the switch 4. The closing of the contacts 33 of the relay 16 associated with the switch 4, due the load circuit 1 being deenergized, does not effect the immediate closing of the switch 4 under the conditions assumed because the above traced circuit for the control relay 17 is now open at the contacts 37 of the associated lockout relay 10.

hen the switch 4 opened, it closed its auxiliary contacts 35 and completed a circuit for the release magnet 27 of the timing device 20 associated with the switch 4 so that its stop 25 is moved out of engagement with the projection 26 and the timin device is set into op eration. The circuit or the release magnet 27 is from one side of a suitable source of control current through the auxiliary contacts 35 on the switch 4, contacts 39 of the lockout relay 10, contacts 40 of the voltage relay 21, contacts 41 of the lockout relay 22, contacts 34 or" relay 16, coil of the release magnet 27 to the other side of the control circuit.

After the timing device has been in operation for a predetermined time it closes its contacts 28 and completes a circuit for its control relay 30. The circuit of the control relay 30 includes the auxiliary contacts 35 on the circuit breaker 4, contacts 39 of the lockout relay 10, contacts 40 of the voltage relay 21, contacts 41 of the lockout relay 22 and contacts 34 of the relay 16. The control relay 30 by closing its contacts 43 completes a locking circuit for itself which is independent of the contacts 28 so that when the timing device subsequently opens these contacts the control relay 30 is not deenergized. When the timer 23 subsequently closes its contacts 29 a circuit is completed for the control relay 17 to effect the closing of the switch 4 if the relay 30 is still energized. This circuit is from one side of a suitable source of control current through the auxiliary contacts 35 on the switch 4, coil of relay 17, contacts 36 of the undervoltage release magnet 9, contacts 29 of the timing device 20, contacts 43, of the control relay 30 to the other side of the control circuit. The energization of the control relay 17 effects, in the manner above described, the energization of the closing coil 6 of the switch 4 so that this switch is closed and the source 2 is reconnected to the load circuit 1. The switch 4 in closing, opens its auxiliary contacts 35 so that the control relay 30 is deenergized and opens its contacts 43, thereby preventing another energization of the control relay 30 until the timer 23 again closes its contacts 28.

If the overload on the load circuit 1 has been removed at the time the switch 4 is reclosed the switch 4 remains closed and subsequent closures of the contacts 28 and 29 of the timer 23 associated with the switch 4 do not effect the completion of the circuit of the associated control relay 30 as the circuit of this relay is open at the auxiliary contacts 35 on the switch 4 and also at the contacts 34 of the associated voltage relay 16.

When the timer 23 associated with. the switch 4 reaches its lockout position and closes its contacts 31 a circuit is completed for the release coil 14 of the lockout relay 10 so that this relay is reset to its normal position. The circuit of the release coil 14 also includes the auxiliary contacts 46 on the switch 4 which is closed. The timer 23 continues to rotate until it reaches its normal position where it is stopped by the projection 26 engaging the stop 25 which is in the path of movement of the projection 26 since the release magnet 27 is deenergized.

It the overload on the load circuit is a permanent one the overload relay 11 associate-d with the source 2 effects the opening of the switch 4 immediately after it is reclosed and the timing device 20 associated with switch 4 by closing the contacts 28 and 29 main effect the reclosure of the switch 4 after a predetermined time. The successive clos- 1 P du ing and opening of the switch 4 continues un til the timing device 20 reaches its lockout position and closes its contacts 31. A circuit is now completed for the lockout relay 22 through the contacts 31 of the timer 28 and the contacts 42 of the voltage relay 16 which under the conditions assumed, is deenergized. The lockout relay 22 by opening its contacts 41 decnergizes the release magnet 27 of the timing device 20 and also opens the circuit of the control relay 30 so that the timing device is stopped when it reaches its normal position and further reclosing of the switch 4 is pre vented.

It will be observed that when an overload occurs on the load circuit 1 the automatic control equipment associated with the switch operates in a similar manner to close the switch 5 a predetermined number of times and to lock out the switch against further reclosures if the load circuit voltage is not restored to its normal value when the timing device 20 associated with the switch 5 reaches its lockout position. By varying the relative time settings of the two timing devices 20 any desired reclosing sequence of the switches 4 and 5 may be obtained.

It the overload is removed before both timing devices reach their respective lockout positions, the first switch to be closed, after the removal of the overload, remains closed and as heretofore described the timing device 20 associated therewith is prevented from effecting further reclosures of the closed switch and the associated lockout relay is restored to its normal position when the timing device reaches its lockout position. The timing device associated with the open switch is also arranged to be restored to its normal position without effecting further reclosures of the open switch. IV hen the voltage across the load circuit 1 is restored by one of the switches remaining closed all of the voltage relays 16 remain energized so that their respective contacts 3 lare open. Therefore, when the timing device associated with the open switch again closes its contacts 28 the associated control relay 30 is not energized. he timing device is stopped when it reaches its normal position because the circuit 01 the associated release magnet 27 is also open at the contacts 3 1- of the voltage relay 16. When the timing device associated with the open switch reaches its lockout position a circuit is completed for the release coil 14; of the associated lockout relay 10 to restore it to its normal position. This circuit of the release coil includes the contacts 31 oi the timing device, contacts32 of the associated voltage relay 16 and auxiliary contacts 4-8 on the open switch.

IVhile I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing or" said switch when the voltage of said load circuit decreases below a predetermined value while said switch is open, means responsive to an overload on said source for effecting the opening of said switch, and means controlled by said overload responsive means for rendering said voltage responsive means inoperative to effect the immediate closing of said switch when said load circuit becomes deenergized due to said switch being opened in response to an overload on said circuit.

2. In combination, a load circuit, a source oi"? current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value while said source is disconnected from said circuit, means responsive to an overload on said source for effecting the opening of said switch, lockout means responsive to the operation of said overload responsive means for rendering said voltage responsive means inoperative to etfect the immediate closing of said switch, and means controlled by said voltage responsive means for resetting said lockout means so as to render said voltage responsive means again operative to effect the immediate closing of said switch when the voltage of said circuit is subsequently restored to a predetermined value.

' 3. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value while said switch is open, means responsive to an overload on said source for effecting the opening of said switch, lockout means responsive to the operation of said overload responsive means for rendering said voltage responsive means inoperative to effect the immediate closing of said switch, and means responsive to the restoration of a. predetermined voltage across said load circuit for resetting said lockout means.

43. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value while said switch is open, means responsive to an overload on said source for effecting the opening of said switch, a lockout relay controlled by said overload responsive means for rendering said voltage responsive means inoperative to effect the closing of said switch, a release coil for said relay, and means controlled by the position of said switch and the voltage of said circuit for controlling the energization of said release coil.

5. In combination, a load circuit, a source of current, a switch for connecting said source to said circuit, electroresponsive means arranged when energized to effect the closing of said switch, a relay responsive to the voltage of said circuit, an energizing circuit for said electroresponsive means normally arranged to be completed by said voltage relay when the voltage of said circuit is below a predetermined value, and lockout means responsive to the current output of said source for effecting the opening of said energizing circuit and for maintaining said energizing circuit open.

6. In combination, a load circuit, a source of current, a switch for connecting said source to said circuit, electroresponsive means ar ranged when energized to effect the closing of said switch, a relay responsive to the volt age of said circuit, an energizing circuit for said electroresponsive means normally arranged to be completed by said voltage relay when the voltage of said circuit is below a predetermined value, normally closed contacts in said energizing circuit, a lockout relay responsive to the current output of said source for opening and maintaining said contacts open, a release coil for said lockout relay, and means controlled by the position of said switch and the voltage of said load circuit for controlling the energization of said release coil.

7. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value, means responsive to an overload on said source for effecting the opening of said switch, means controlled by said overload responsive means for rendering said voltage responsive means inoperative to effeet the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value and for effecting the closing of said switch after it has been open a predetermined time.

8. In combination, a load circuit, a source of current disconnected from said circuit, a

switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value, means responsive to an overload on said source for effecting the opening of said switch, timing means arranged when operated to effect the closing of said switch after a predetermined time, and means controlled by said overload responsive means for rendering said voltage responsive means inoperative to effect the immediate closing of said switch and for effecting the operation of said timing means.

9. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged'to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value, means responsive to an overload on said source for effecting the opening of said switch, timing means ar ranged when openated to effect the closing of said switch after a predetermined time, means controlled by said overload responsive means for rendering said voltage responsive means inoperative to efiect the immediate closing of said switch and for effecting the operation of said timing means, and means controlled by said timing means and the position of: said switch for rendering said voltage responsive means again operative to con rol the closing of said switch.

10. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value, means responsive to an overload on said source for effecting the opening of said switch, timing means arranged when operated to effect the closing of said switch a plurality of times with predetermined time intervals between successive closures, and means controlled by said overload responsive means for rendering said Voltage responsive means inoperative to effect the immediate closing of said switch and for effecting the operation of said timing means.

11. In combination, a load circuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to'eflect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value, means responsive to an overload on said source for effecting the opening of said switch, timing means arranged when operated to effect the closing of said switch after a predetermined time interval, a lookout relay controlled by said over load responsive means for rendering said voltage responsive means inoperative to effect the immediate closing of said switch and for effecting the operation of said timing means, a release coil for said lockout relay arranged when energized to effect the restoration of the lockout relay to its normal position, and means controlled by said timing means and said switch for effecting the energization of said release coil if said switch is closed after said timing means has been in operation a predetermined time.

12. In combination, a load ci 'cuit, a source of current disconnected from said circuit, a switch for connecting said source to said load circuit, means responsive to the voltage of said circuit normally arranged to effect the immediate closing of said switch when the voltage of said load circuit decreases below a predetermined value, means responsive to an overload on said source for effecting the opening of said switch, timing means arranged when operated to effect the closing of said switch after a predetermined time intcrval, a lockout relay controlled by said overload responsive means for rendering said voltage responsive means inoperative to effect the immediate closing of said switch and for effecting the operation of said timing means, a release coil for said lockout relay arranged when energized to effect the restoration of the lockout relay to its normal position, and

1 means controlled by said timing means and said voltage responsive means and the position of said switch for controlling the energization of said release coil whereby said release coil is energized if said switch is open and the voltage of said load circuit is above a predetermined value after said timing means has been in operation a predetermined time.

13. In combination, a load circuit, two sources of current for said load circuit, a switch between one of said sources and said load circuit, means responsive to a failure in the voltage of said load circuit when said other source is connected to said circuit and said switch is open for effecting the immediate closing of said switch, timing means for reclosing said switch a plurality of times with predetermined time intervals between successive closures, and means responsive to the current output of said one of said sources when connected. to said load circuit for rendering said immediate closing means inoperative and for effecting the opening of said switch and the operation of said timing means.

14:. In combination, a load circuit, two sources of current for said load circuit, a switch between one of said sources and said load circuit, means responsive to the voltage of said load circuit for effecting the immediate closing of said switch when said other source is connected to said load circuit and the voltage of said circuit decreases below a predetermined value, timing means for reclosing said switch after a predetermined inter 

